The present invention relates generally to an encapsulated endoluminal stent comprising a stent inseparably encased between at least two polytetrafluoroethylene grafts. In accordance with the preferred embodiments of the present invention, the grafts are tubular grafts are longitudinally expanded polytetrafluoroethylene tubular extrudates (ePTFE) and the stent is a pressure-expandable stent. The present invention also provides a method for making the inventive ePTFE encapsulated stent and a method for endoluminal delivery of the inventive ePTFE encapsulated stent. More particularly, a first preferred embodiment of the present invention relates to a radially balloon-expandable encapsulated stent for endovascular delivery which comprises a balloon-expandable tubular stent member interdisposed between two radially balloon-expandable tubular ePTFE grafts. The two radially balloon-expandable tubular ePTFE grafts are made by extruding a PTFE-lubricant mixture through a ram extruder into a tubular shaped extrudate and longitudinally expanding the tubular extrudate to yield a uniaxially oriented node-fibril microstructure in which substantially all of the fibrils in the ePTFE microstructure are oriented parallel to one another in the axis of longitudinal expansion. ePTFE tape or sheet materials may be substituted for the tubular ePTFE grafts.
The method of making the encapsulated stent generally includes the steps of providing a first tubular ePTFE graft member about a mandrel, concentrically positioning a pressure-expandable stent over the first ePTFE graft member such that the first tubular ePTFE graft member covers at least a substantial extent of the luminal surface of the stent, and concentrically positioning a second tubular ePTFE graft member over the stent such that the second tubular ePTFE graft member covers at least a substantial extent of the abluminal surface of the stent, applying an external positive circumferential pressure or an internal radial pressure to assembly to cause a physical interaction and adhesion between the node-fibril microstructure of the first and second ePTFE graft members through wall openings in the stent, and fully sintering the stent-graft assembly to create a substantially monolithic encapsulation of the stent.